U-602796, Application for Amend to License NPF-62,requesting Temporary Partial Exemption to 10CFR50,App A,General Design Criteria 17 Re Offsite Circuit Condition. Condition
| ML20149J165 | |
| Person / Time | |
|---|---|
| Site: | Clinton  |
| Issue date: | 07/22/1997 |
| From: | Romberg W ILLINOIS POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20149J168 | List: |
| References | |
| U-602796, NUDOCS 9707280091 | |
| Download: ML20149J165 (19) | |
Text
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.,5 lii nois Power Company Chnton Power Station P O Box 678 l
l Cienton, IL 61727 Tet 217 935-6220 Fax 217 935-4632 Wayne D. Romberg P@
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July 22,1997 l
Docket No. 50-461 10CFR50.90 Document Control Desk 9
j Nuclear Regulatory Conunission Washington, D.C. 20555
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Subject:
Application for Temporary Partial Exemption from 10CFR50 Appendix l
A General Design Criterion 17 and Amendment of Facility Operating License No. NPF-62 for Clinton Power Station (LS-97-004)
Dear Madam or Sir:
During the current refueling outage at Clinton Power St: tion (CPS), Illinois Power Company (IP) recently determined that, for short and intermittent periods of l/g g
time, voltage on one of the offsite electrical power circuits for CPS is not able to be i
maintained above the minimum required value conservatively established for CPS. This is primarily due to the fact that unusually low voltages are occurring as a result of the current lack of operating generators in Illinois, coupled with high load demands during OO/
peak hours. All possible measures, short ofinterrupting service to customers, have been taken to support the offsite circuit voltage. Notwithstanding, IP believes that plant operation is justified considering that continually acceptable voltage has been indicated for the other offsite circuit, and measures have been taken to ensure operators will know when voltage on the vulnerable offsite circuit may be inadequate in the event of a plant
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trip.
i This issue was discussed in a meeting between NRC staff and IP personnel on July 17,1997, with the intent of achieving a resolution to the issue that would support IP's scheduled plant startup fiom the current refueling outage. Based on the meeting discussion, a means to temporarily resolve this issue via the license amendment process was proposed. However, during subsequent teleconferences with the NRC Staff the conclusion was reached that the 10CFR50.12 exemption process was necessary to implement the proposed changes. Accordingly, pursuant to 10CFR50.12 and 10CFR50.90, IP hereby applies for a temporary partial exemption to 10CFR50 Appendix A, General Design Criteria (GDC) 17, and amendment of the CPS Operating License, No. NPF-62. The proposed temporary partial exemption to the requirements hl l
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9707280091 970722 PDR ADOCK 05000461 P
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U-602796 Page 2 of 3 of GDC,17 as defined by our current licensing basis will allow plant operation while one of the two independent offsite electrical circuits is experiencing intermittent periods ofless
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than the minimum required voltage. The amendment and exemption, as proposed, would j
be effective immediately (i.e., upon NRC approval) through and including October 15, 1997.
To reflect IP's intention to operate CPS with the identified offsite circuit 4
i condition, and based on a temporary partial exemption to GDC 17, IP proposes to revise paragraph 2.D of the Operating License, Technical Specification (TS) Section 3.8.1, "AC Sources - Operating," and the Bases for TS Section 3.8.1. Under the proposed changes to the Technical Specifications, the Limiting Condition for Operation (LCO) of TS 3.8.1 L
could continue to be satisfied (for the period that the amendment and exemption is in effect) with one qualified offsite source and one offsite source that does not strictly
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conform to the capacity and capability requirements of GDC 17. However, with two offsite sources not strictly conforming to the capacity and capability requirements of GDC 17, both sources must be declared inoperable, which would require entry into the Required Actions of Condition C. (The latter requires a plant shutdown to be initiated if one offsite source cannot be restored in 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.) Condition C normally applies with two sources inoperable, and Condition A normally applies with one offsite source inoperable.
IP is thus proposing to enter the more conservative Action statement with two sources not strictly meeting GDC 17 requirements due to reduced voltage. However, it should be i
noted that during the effective period of the amendment / exemption, there may be occasions where Condition C may be entered for short periods of time. Although this may occur on consecutive days, it is expected that the cumulative period of time will be less i
than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. These are expected to be few, and only occur during a period of severe demand (i.e., extremely hot weather and/or reduced generating capacity). In the event that both the 138-kV and the 345-kV systems are predicted to have less than the required voltage upon loss of the CPS generator, the indicated relative risk (in terms of core damage probability) of continuing to operate for a short duration (4E-6, for a 24-hour period) is significantly less than the risk associated with a controlled plant shutdown (4E-5). If this cumulative time is approached, IP will notify the NRC to discuss appropriate compensatory actions.
5 A description of the proposed changes and associated justification (including a i
Basis For No Significant Hazards Consideration) are provided in Attachment 2. A marked-up copy of the affected pages from the Operating License is provided in i
l. A marked up copy of the affected pages from the TS is provided in. A marked up copy of the affected pages from the TS Bases is provided in. An Environmental Assessment is included in Attachment 6. Further, an affidavit supporting the facts set forth in this letter and its attachments is provided in. Following NRC approval of this request, IP will revise the CPS TS Bases in accordance with TS 5.5.11, " Technical Specification (TS) Bases Control Program," to i
incorporate the changes identified in Attachment 5.
Currently, CPS is in a shutdown condition (Mode 4) for its sixth refueling outage (RF-6). IP is scheduled to commence restart of the plant on July 28,1997. This temporary partial exemption and corresponding license amendment are needed prior to l
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Page 3 of 3 resuming operation, and failure of the NRC to act in a timely manner would delay the planned startup. Unique circumstances have arisen this summer which collectively result in high demands on the electrical transmission systems connected to CPS. These circumstances include, new limits on the allowable range of voltage required for CPS operation, an unforeseen low regional generating capacity due to extended outages at a large number of neighboring power plants, combined with high peak demands during hot-weather days. While the situation does not present a challenge to grid stability, this combination of events has caused periods orlow system voltages such that this temporary partial exemption and corresponding license amendment request have become necessary.
In light of these circumstances and the need to support plant startup, IP respectfully requests prompt NRC review and approval of this application for a temporary partial exemption from the requirements of 10CFR50, Appendix A, GDC 17, as well as review and approval of the associated license amendment on an emergency basis in accordance with 10CFR50.91(a)(5).
Sincerely yours,
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Wayne D. Romberg Assistant Vice President JFK/eem Attachments cc:
NRC Clinton Licensing Project Manager l
NRC Resident Office, V-690 Regional Administrator, Region III, USNRC Illinois Department of Nuclear Safety j
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to U-602796 Wayne D. Romberg, being first duly sworn, deposes and says: That he is Assistant Vice President ofIllinois Power; that this application for partial exemption from General Design Criterion 17 of10CFR50 Appendix A and for amendment ofFacility Operating License NPF-62 has been prepared under his supervision and direction; that he knows the contents thereof; and that to the best of his knowledge and belief said letter and the facts contained therein are true and correct.
Date: This M day of July,1997.
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Signed:
Wayne D. Romberg STATE OF ILLINOIS l SS.
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f DEWITT COUNTY J
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Subscribed and sworn to before me this 22 *J day ofJuly 1997.
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(Notary Public)
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LS-97-004 i
Page 1 of 11 i
CPS Electrical Distribution System 1
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10CFR50, Appendix A, General Design Criterion (GDC) 17, Electrical Power Systems, requires that an onsite and an offsite electric power system be provided to permit -
l functioning of structures, systems, and components important to safety. The safety function for each of these two systems (assuming the other system is not functioning) is to j
provide sufficient capacity and capability to assure that: (1) specified acceptable fuel i
design limits and design conditions of the reactor coolant pressure boundary are not exceeded as a result of anticipated operational occurrences, and (2) the core is cooled and containment integrity and other vital functions are maintained in the event of postulated accidents.
GDC 17 also requires that electric power from the transmission network to the onsite electric distribution system shall be supplied by two physically independent circuits (not necessarily on separate rights of way) designed and located so as to minimize to the extent practical the likelihood of their simultaneous failure under operating and postulated
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accident and environmental conditions. Additionally, each of these circuits is required to be designed to be available in sufficient time following a loss of all onsite alternating current power supplies and the other offsite electric power circuit, to assure that specified acceptable fuel design limit and design conditions of the reactor coolant pressure boundary j
are not exceeded. One of these circuits shall be designed to be available within a few seconds following a loss-of-coolant accident to assure that the core cooling, containment integrity, and other vital safety functions are maintained.
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Evaluation of the CPS electric power system against GDC Criterion 17 is described in the Clinton Power Station (CPS) Updated Safety Analysis Report (USAR) i Section 3.1.2.2.8.1. Onsite and offsite electric power systems are provided for CPS to permit the functioning of structures, systems and components important to safety. The i
i Class IE electric power system for CPS consists of three electrically and physically independent distribution divisions. The onsite power supplies for each of these three divisions consist of a diesel generator and a battery supply. (A fourth Class IE battery l
supply is utilized for portions of the emergency core cooling and reactor protection l
systems.) Class IE loads with redundant safety functions are assigned to redundant i
divisions. The redundancy of the Class IE load functions is such that the nuclear safety of the station is not degraded when electrical power is lost to one division due to a single failure.
f The three redundant distribution divisions which comprise the onsite electric power system are supplied with electric power from the transmission network via two
- physically independent circuits. One of these offsite circuits is a 345-kV circuit (fed by three transmission lines) from the switchyard through the Reserve Auxiliary Transformer L
(RAT), and the other is a 138-kV circuit (fed by one transmission line) from the IP grid
- system through the Emergency Reserve Auxiliary Transformer (ERAT). The 138-kV and 345-kV transmission lines used as the offsite powe supplies are on physically separate j
rights of way and are electrically independent as described in USAR section 8.2.1.1 and i
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LS-97-004 Page 2 of 11 l
8.2.2.1. The 345-kV and 138-kV transmission lines and their associated structures are 4
designed to successfully withstand enviromnental conditions prevalent in the area (wind, temperature, lightning, flood, etc.), thus minimizing simultaneous failure.
l Chapter 15 of the USAR discusses the effects of anticipated process disturbances to determine their consequences and the capability of the plant to control or accommodate such events. Subsection 15.2.6 discusses loss of AC power, including loss of grid. This j
discussion demonstrates that fuel design limits and reactor coolant pressure boundary
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design conditions are not exceeded.
Backaround i
. Prior to the current refueling outage (RF-6) at Clinton Power Station (CPS),
Illinois Power (IP) recognized that with offsite voltage at its minimum expected value, the I
auxiliary electrical power distribution system at CPS may not provide adequate voltage to certain plant electrical loads at the 120-volt level. Modifications were thus planned to j
replace certain 120-volt distribution transformers with regulating transformers to regulate voltage for the potentially affected loads. In addition, because it was also previously l
recognized that the degraded voltage protection relays and their setpoints were not sufficient to provide automatic degraded voltage protection over the full range of voltage l
to ensure proper operation of all Class IE equipment, modifications were also planned for i
installing new, more accurate relays for proper degraded voltage protection. (Amendment i
l10 to the CPS Operating License was issued to support installation of the new relays l
with new setpoints.)
Installation of the relays for all three safety-related 4160-V buses at CPS was completed during RF-6. However, upon installation of the first of the 120-V regulating transformers, a problem was experienced. The new transformers were found to be particularly sensitive to radio frequency and electromagnetic interference such that their internal protective circuitry was causing spurious trips of one of the transformers. It was therefore decided to reinstall the original non-regulating transformers for the 120-V g
distribution panels. A new approach to resolving the long-term prcblem is currently under l
development, but in the short term (i.e., during the current refueling outage) it was determined that other changes would be made to the auxiliary power system to ensure adequate voltage to the critical 120-volt loads. The changes involved changing the tap settings on the Reserve Auxiliary Transformer (RAT), Emergency Reserve Auxiliary Transformer (ERAT), and selected distribution transformers to provide an overall boost in voltage to the critical 120-volt loads. Extensive calculations at a very detailed and unprecedented level were performed to support these changes as careful consideration had to be given to providing the needed boost in voltage to the critical 120-volt loads without excessively boosting voltage to other plant loads. The most recently determined value for the minimum expected offsite voltage through 1998 (as determined by a model provided l
by the Mid-America Interconnected Network (MAIN)) was utilized in these calculations.
The transformer modifications were completed in late June,1997.
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LS-97-004 4
Page 3 of11 1
Also during late June,1997, IP began to closely monitor voltage on the 138-kV 4
and 345-kV systems (while the plant was still offline). This was prompted by the fact that, j
at times, voltages were lower than anticipated. IP was concerned that the current situation in the midwestern United States, i.e., the current lack of generating capacity due j
to the number of shutdown units, combined with periods of peak summer demand during F
hot weather, may cause periods of unusually low voltage on the 138-kV and 345-kV systems. CPS Operations worked with the IP Dispatch Center to establish measures for specifically maintaining voltage on both of the systems at CPS at an acceptable level.
l These measures consist of: (1) switching capacitor banks on the system, (2) increasing VAR output from other geneating units, and (3) switching /reconfiguring the system.
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- Additionally, in anticipation of plant startup, a " predictor model" is being utilized l
to be able to inform operating personnel of when offsite circuit voltages may be less than j
the minimum required value for CPS following a plant trip. This was necessary since, while CPS is supplying power to the grid, voltages are normally higher than when the plant is offline, and thus the true offline voltage condition could be masked. The predictor
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model considers system configurations and predicted daily load demands to determine I
minimum expected grid voltages at CPS for the day. Monitoring the 345-kV and 138-kV l
system voltages while the plant was offline provided a means of validating the accuracy of l
the predictor model.
l For the period between June 23 and July 20,1997 (28 days), monitoring of the 345-kV system voltage yielded the following results:
18 days where system voltage was always greater than minimum required.
e During the total observed period of 670 hours0.00775 days <br />0.186 hours <br />0.00111 weeks <br />2.54935e-4 months <br />, system voltage was less than minimum required for a total of only 73 hours8.449074e-4 days <br />0.0203 hours <br />1.207011e-4 weeks <br />2.77765e-5 months <br />.
l For the period between June 25 and July 20,1997 (26 days), monitoring of the 138-kV system voltage demonstrated that voltage remained above the minimum required level throughout the entire period.
The voltages seen for the 345-kV system during this period were lower than what was anticipated. In anticipation of the summer demand it was expected that implementation of the previously described measures would be sufficient for maintaining i
j offsite circuit voltages. As noted above, success was achieved for the 138-kV system, but the 345-kV system has demonstrated that it cannot be maintained such that its voltage will be greater than the minimum required level 100 percent of the time for the remainder of i
the summer without curtailing electrical service to customers. However, a simulated i
emergency exercise conducted by the IP Dispatch Center on July 16,1997, demonstrated that in the event of an accident at CPS, offsite electrical supply voltages can be fully j
recovered in a reasonably short period of time (approximately 15 minutes) by shedding other loads on the system. Similarly, in the unlikely event that 138-kV system voltage is less than the minimum required level while the 345-kV system has adequate voltage, IP has determined that 138-kV system voltage can be restored in the same time frame.
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LS-97-004 Page 4 of 11 1
i The unexpected difficulty with offsite circuit voltage this summer prompted IP to reevaluate the design basis for CPS relative to GDC 17. On the basis that the 138-kV system voltage can be maintained within acceptable limits, and that a low-voltage condition on the 345-kV system can be quickly recovered if necessary (or conversely, that the 345-kV system voltage can be maintained within acceptable limits, and that a low voltage condition on the 138-kV system can be quickly recovered if necessary) IP's position is that a power supply configuration with one offsite circuit greater than minimum f
required voltage and one offsite circuit that intermittently exhibits less than minimum required voltage, but is quickly recoverable if necessary, still in fact meets the underlying 1
purpose of GDC 17.'
Meeting Conducted with NRC on July 17.1997 i
On July 17,1997, a meeting between IP and NRC staff personnel was conducted i
to discuss the offsite voltage situation for CPS and IP's position regarding continued conformance to GDC 17. IP reviewed the issues and events leading to the current 4
situation, including the unforeseen difficulty with maintaining 345-kV system voltage within the limits recently established for CPS. IP presented its position that plant operation with low (but recoverable if necessary) voltage on one of the two offsite circuits l
is consistent with the underlying purpose of GDC 17 and thus still meets the i
design / licensing basis for the facility. The NRC staff disagreed with IP's position.
j Although the CPS design (under normal conditions) more than meets the requirements of i
GDC 17, the NRC staff's position is that the CPS licensing basis assumes two independent, offsite dreuits with greater than the minimum required voltage.
Implementation ofIP's position would thus constitute a change to the CPS licensing basis, and requires NRC approval.
Following the July 17 meeting, a follow-up teleconference between IP and NRC staff personnel was conducted to further discuss the issue. In that follow-up discussion j
the NRC expressed its position that although GDC 17 requires only one of the two offsite circuits to be immediately available (i.e., within a few seconds following a loss-of-coolant accident), the GDC also states, "The safety function for each system (i.e., the onsite electric power system and the offsite electric power system] shall be to provide suffcient capacity andcapability to assure that (1) specified fuel design limits and design conditions of the reactor coolant pressure boundary are not exceeded as a result of anticipated i
operational occurrences and (2) the core is cooled and containment integrity and other vital functions are maintained in the event ofpostulated accidents." [ emphasis added] An offsite circuit having less than the required minimum voltage, according to the NRC's staff position, is not a source that has afficient capacity and capability, regardless of the fact that, in the event the circuit is needed, the voltage may be quickly recovered (by shedding load for example). Thus, a partial exemption from the requirements of GDC 17 is required to implement the changes proposed by IP.
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LS-97-004 Page 5 of 11 Description of Proposed Channe In accordance with 10CFR50.12, IP is requesting a temporary partial exemption from the requirements of 10CFR50 Appendix A GDC 17. GDC 17 specifically requires the availability of two physically independent offsite electrical circuits of sufficient capacity and capability. The temporary partial exemption is requested for the intermittent periods l
during peak summer demand that the grid voltage, and thus its capacity and capability, is i
below the minimum required levels as calculated for CPS. This temporary partial exemption and corresponding license amendment will only be effective from the date of i
issuance up to and including October 15,1997.
j In accordance with 10CFR50.90, the following changes to Operating License No.
l NPF-62 for CPS are being proposed:
(1)
Paragraph 2.D is being revised to acknowledge the proposed temporary partial exemption to the requirements of GDC 17 to allow plant operation while one of the two independent offsite electrical circuits is experiencing intermittent (but quickly recoverable if necessary) periods ofless than minimum required voltage.
In addition, this revision acknowledges that the special circumstances associated with this proposed exemption will be addressed in the safety evaluation report accompanying the associated amendment to the Operating License.
(2)
A note for Technical Specification (TS) LCO 3.8.1, "AC Sources - Operating," is being added to clarify that for the period that the amendment and exemption is in effect, the LCO requirement for two qualified offsite circuits can be satisfied with l
one qualified offsite source and one offsite source that does not strictly conform to the capacity and capability requirements of GDC 17. However with two offsite sources not strictly conforming to the capacity and capability requirements of GDC 17, both sources must be declared inoperable."
These proposed changes will also be reflected in the Bases for TS 3.8.1 as described in. The TS Bases proposed change will clarify what action must be taken in the event that voltage on either or both of the offsite circuits is less than the minimum required level. As discussed later, IP has determined that the proposed change involves no significant hazards consideration.
Justification for Proposed Channe As discussed previously, IP's current licensing basis is based on the CPS design in which the two independent offsite electric power circuits for CPS (required to be continuously connected or OPERABLE per CPS TS 3.8.1) have sufficient capacity and capability to satisfy the requirements of GDC 17. IP proposes that conducting plant operations with the voltage of one offsite circuit less than the minimum required voltage, is acceptable. Although this is a reduction in the level of conun tment established by IP's i
original licensing basis, this configuration continues to satisfy the underlying purpose of
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GDC 17 for an acceptable design, as further discussed below. It should be emphasized that this configuration is not continuous (it exists only intermittently) and is not long term i
(it is expected to no longer exist after summer concludes). Therefore, the requested amendment is intended to be effective from the date ofissuance up to and including i
October 15,1997.
2 The following is an evaluation ofIP's proposed change against each of the four j
j criteria contained in GDC 17 regarding required offsite electric power supplies / circuits:
1 (1) " Electric power from the transmission network to the onsite electric distribution
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system shall be supplied by two physically independent circuits (not necessarily on i
separate rights of way) designed and located so as to minimize to the extent practical the j
likelihood of their simultaneous failure under operating and postulated accident and environmental conditions."
i CPS Evaluation: CPS compliance with this requirement is unaffected as the proposed j
change does not change the design of the offsite electric power circuits with respect to j.
their independence and the likelihood of simultaneous failure.
(2) " Provisions shall be included to minimize the probability oflosing electric power from any of the remaining supplies as a result of, or coincident with, the loss of power generated by the nuclear power unit, the loss of power from the transmission network, or 1
the loss of power from the onsite electric power supplies."
CPS Evaluation: Because the proposed change does not affect the independence of the onsite und offsite electric power supplies, it does not increase the probability oflosing i
power from any of the remaining supplies as a result of the loss of power from the i
transmission network (i.e., the other offsite circuit) or the loss of power from the onsite power supplies. The probability of failure of the remaining supplies occurring coincident with an offsite circuit being degraded due to low voltage is increased, but the probability of such coincident random failures will still be quite small. With regard to the probability of completely losing the offsite circuit that is degraded by low voltage and is separated from the plant by the degraded voltage protection relays following a plant trip, IP has demonstrated that the source voltage (and thus the offsite circuit) can be quickly recovered if necessary.
1 (3) "One of these [offsite electric power] circuits shall be designed to be available within L
a few seconds following a loss-of-coolant accident to assure that core cooling,
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containment integrity, and other vital safety functions are maintained."
I CPS Evaluation: With one offsite circuit experiencing less than minimum required i
voltage, the remaining offsite circuit will continue to be required to maintain voltage l
greater than the minimum required level. By design, each of the two offsite circuits for CPS is normally continuously available. Thus, either source is capable of being "available within a few seconds" following a loss-of-coolant accident.
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LS-97-004 Page 7 of 11 (4) "Each of these (offsite electric power] circuits shall be designed to be available in sufficient time following a loss of all onsite alternatin8 current power supplies and the other offsite electric power circuit, to assure that specified acceptable fuel design limits and design conditions of the reactor coolant pressure boundary are not exceeded."
CPS Evaluation: As noted above, each of the offsite electric power circuits is (normally) an immediate access circuit. Through discussion with the IP electrical dispatch center, and by performance of an emergency exercise at the dispatch center to determine how long it would take to recover voltage on an offsite circuit having less than the minimum required voltage during an emergency at CPS (loss of all onsite and offsite AC power), IP determined that voitt.e;e can be quickly recovered through the interruption of power service to customers. The expected time is less than the amount of time accepted for many plants where aligning the delayed access circuit may involve disconnecting links or performing switching operations or breaker realignments in order to connect the credited circuit. Further, although conditions are not fully comparable, as an additional gauge on the acceptability of the recovery or delay time determined for restoring voltage on a degraded circuit, IP's coping analysis for a station blackout as defined in 10CFR50.2 indicates the capability to withstand a Station Blackout (SBO) of four hour duration.
As noted previously, due to the problem encountered with the plant modification involving the installation of regulating transformers during the current refueling outage, and the subsequent decision to not proceed with that modification, IP determined to make what adjustments or changes it could to the existing auxiliary power system to provide adequate voltage to the critical 120-volt loads. The calculations required to support that effort were extremely extensive and detailed and were focused to an unprecedented degree down to the 120-volt level. This resulted in well-founded but more limiting required plant voltage values at the 4160-VAC safety bus level when the 120-volt required load voltages were reflected at that level. It was also recognized that there would be reduced operating margins with respect to offsite circuit voltages as the summer approached, but IP's expectation was that suflicient measures could be taken to maintain offsite voltage above the levels req 6 ired to support CPS. In addition, the current unavailability of generators in Illinois and the increased summer demand have contributed to offsite circuit voltages that are lower than expected, particularly on the 345-kV system. All possible measures have been taken to boost grid voltage during high demand, short ofinterrupting service to IP's customers, but these measures have not been successfulin ensuring that the 345-kV system voltage meets or exceeds the minimum requirement for CPS.
CPS has evaluated the risk associated with having one ofDite electric circuit experiencing less than the minimum required voltage for a certain percentage of the time while the plant is operating. The risk evaluation has shown that for the risk associated with having the safety related buses on the ERAT, concurrent with low predicted voltage on the RAT, the Core Damage Frequency (CDF)is 2.67E-5 events per year. By comparison, the base CDF is 5.55E-6 events per year. It may also be noted that the associated risk is further reduced due to the likelihood that predicted voltage will not be low dudng the later part of the effective period for the exemption (as the weather becomes
1 to U-602796 LS-97-004 Page 8 of11 cooler). The resultant annual average CDF is 6.16E-6 events per year, which represents an 11 percent increase above the base CDF.
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The above result is based on plant loads being aligned to the ERAT. However, the above does not include consideration of the separate reliability history for the 138-kV and d
345-kV systems. Generally, in light of the three transmission lines normally connected to j
. the 345-kV switchyard bus, the RAT /345-kV system is considered more robust than the single-line 138-kV system / ERAT (notwithstanding the intermittent low-voltage condition prevalent on the 345-kV offsite circuit). Thus, although the above risk data indicates a
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preference for the ERAT, loads will be aligned to the RAT for significant periods of time during the effective period of the exemption / license amendment. This is due in part to the potential for an inadvertent plant trip associated with switching loads from one offsite source to the other. In light of this concern, switching will be minimized to keep that potential as low as possible.
In view of the above, and in anticipation of plant startup from the current refueling 2
outage, the previously described predictor model is being utilized to enhance IP's capability to ascertain what the grid voltage situation is while CPS is on line supporting the grid, compared to what the grid voltages would be in the event that CPS would trip or be forced to shut down. This tool allows CPS personnel to estimate grid voltage if CPS i
I came offline. IP believes that this effort reflects a conservative approach that balances risk concerns with the need for plant operation to support the needs oflP's customers. Given j
that GDC 17 provides the primary criterion for an acceptable offsite source configuration, and given that IP's proposed change supports a configuration that achieves the underlying i
purpose of GDC 17, through the monitoring of the grid by application of the predictive model, IP believes that operation of CPS in accordance with the proposed change does i
not compromise safety.
Basis for No Significant Hazards Considerations As noted previously, IP proposes to revise the CPS Operating License, Technical Specifications (TS), and TS Bases to allow plant operation when one of the two offsite
- electrical circuits is experiencing less than the minimum required voltage. In accordance with 10CFR50.92, a proposed change to the operating license (or TS) involves no significant hazards consideration if operation of the facility in accordance with the j
proposed change would not: (1) involve a significant increase in the probability or consequences of any accident previously evaluated, (2) create the possibility of a new or different kind of accident from any accident previously evaluated, or (3) involve a significant reduction in a margin of safety. This request is evaluated against each of these criteria below.
(1)
The proposed change involves no physical change to plant systems, structures or components. Further, under the proposed change, CPS will still be required to maintain one of the offsite circuits with greater than the minimum required voltage.
However, the proposed change does permit low voltages to exist on an offsite
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l circuit (relative'to the needs of CPS plant loads) for intermittent periods of time.
This may slightly increase the probability of a failure occurring concurrent with another source inoperable (which could ir volve, for example, an increase in the i
probability of a short term loss of offsite power), or slightly increase the i
probability of a malfunction of safety-related equipment. However, these increases would be expected to be small. Automatic degraded voltage protection for plant loads will not be affected, so there will be continued assurance that loads may j
continue to be supplied by a circuit with adequate voltage. In addition, monitoring l
of the grid condition via the predictor modci will provide a means to qualitatively i
gauge ofiline grid voltage during plant operation so that actions or contingencies may be effected. Therefore, the proposed change does not involve a significant
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. increase in the probability of an accident previously evaluated. On the basis that voltage on one offsite circuit remains greater than the minimum required, the j
proposed change also does not significantly increase the consequences of any accident previously evaluated.
(2)
The proposed change effectively only involves or impacts offsite circuit j
availability. The most severe impact of the proposed change is therefore bounded l
by the loss of offsite power event, and therefore, the proposed change cannot
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create the possibility of a new or different kind of accident.
i (3)
As noted previously, the proposed change does involve or permit intermittent l
periods of time when one of the offsite circuits may have inadequate voltage.
Compared to the currently accepted licensing basis wherein the offsite sources are both required to maintain voltage above the micimum required level, there is a 3
reduction in the margin of safety. However, this reduction in margin is not l
considered to be significant considering the fact that the proposed change allows an offsite circuit configuration that stil! meets the underlying purpose of GDC 17, 4
plant operation with low-voltage condition on one bus is permitted only for limited and ic..mittent periods of time. In addition, the periods of peak load demand that create the intermittent degraded voltage conditibn will diminish when cooler weather returns. The proposed change is temporary on the basis that it will only be effective from the date ofissuance up to and including October 15,1997.
Based on the foregoing, IP concludes that the proposed change does not involve a significant hazards consideration.
l Additional Information i
In accordance with 10CFR50.12(a), the NRC may grant exemptions from the requirements of the regu!ations when special circumstances, as defined in
[
10CFR50.12(a)(2), are present. 10CFR50.12(a)(2)(ii) states that special circumstances 8
exist when application of the regulation in the particular circumstances would not serve the underlying purpose of the rule or is not necessary to; achieve the underlying purpose of the rule. In accordance with 10CFR50.12(a)(2)(iii), special circumstances exist when j
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to U-602796 LS-97-004 Page 10 of11 compliance with the regulation would result in undue hardship or other costs that are significantly in excess of those contemplated when incurred by others similarly situated. In addition,10CFR50.12(a)(2)(v) states that special circumstances exist when the exemption would provide only temporary relief from the applicable regulation and the licensee or applicant has made good faith efforts to comply with the regulation.
The purpose of GDC 17 is to provide criteria for the design of the onsite and offsite electrical distribution systems such that they can each reliably fulfdl their safety functions (assuming the other system is not functioning) of providing sufficient capacity and capability to assure that: (1) specified acceptable fuel design limits and design conditions of the reactor coolant pressure boundary are not exceeded as a result of anticipated operational occurrences, and (2) the core is cooled and containment integrity and other vital functions are maintained in the event of postulated accidents. Since the changes proposed by IP still provide for two physically independent offsite circuits with i
sufficient capacity and capability (albeit, one with greater than the minimum required voltage and one potentially experiencing intermittent periods ofless than minimum required voltage but quickly restorable if necessary by means ofload shedding) to accomplish their safety function, bases are maintained whereby the underlying purpose of GDC 17 is still served. Based en these criteria, IP requests a temporary partial exemption from the requirements of10CFR$0 Appendix A GDC 17.
Reauest for NRC Review and Aotroval on an Emergency Basis (per 10CFR50.91(a)(5))
)
Under certain circumstances, as provided by 10 CFR 50.91, NRC review and approval of a proposed exemption / license amendment can be expedited where failure to act in a timely manner would result in prevention or resumption of plant operation. Given that CPS is scheduled to restart from the current refueling outage on July 28,1997, the processing of this exemption / license amandment application by the normal process would significantly delay plant startup. Thereft re, pursuant to 10 CFR 50.91(a)(5), IP requests j
that this application for exemption / license amendment be processed on an emergency basis.
As explained previously, the unsuccessful plant modification to install regulating voltage transformers resulted in the need to make adjustments and changes to the existing auxiliary power system during the current refueling cutage without the intended voltage regulation. The extensive calculations required to support the auxiliary power system changes and to determine the plant voltage requirements based on the critical plant loads were not completed until later in the outage. Monitoring of the offsite voltages and use -
the aforementioned predictive model were initiated after completion of the calculations.
Further, it has only recently become apparent that IP will not be able to maintain voltage levels on the offsite electrical system above the level required by CPS 100 percent of the tinie. As also explained previously, this is based in part on the unusual, current unavailability of generators in the region and high load demands currently being
- experiened during peak summer hours. These conditions and the need for this requested exemptionhMnse amendment were thus unforeseen. On this basis, and given that the
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a.9 to U-602796 LS.97-004 Page 11 of11 i
proposed exemption / license amendment involves no significant hazards consideration and is needed to proceed with plant startup in the near future, IP believes that there is a need f andjustification for processing the proposed exemption / license amendment on an i
emergency basis.
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~ (8) Post-Fuel loadino initial Test Procram (Section 14. SER. SSER 5 and SSER 6)
Any changes to the initial test program described in Section 14 of the FSAR made in accordance with the provisions of 10 CFR 50.59 shall be reported in accordance with 50.59(b) within one month of such change.
(9) Emeraency Response Capabilities (Generic letter 82-33. Suoolement I to NUREG-0737. Section 7.5.3.1. SSER 5 and SSER 8. and Section 18.
SER. SSER 5 and Safety Evaluation Dated April 17. 1987)
IP in accordance with the commitment contained in a letter a.
l dated December 11, 1986, shall install and have operational separate power sources for each of the fuel zone level channels as provided for in Regulatory Guide 1.97 prior to startup following the first refueling outage.
b.
IP shall' submit a detailed control room design filial supple-mental summary report within 90 days of issdance of the full power license that completes all the remaining items identified in Section 18.3 of the Safeti Evaluation dated April 17, 1987.
D.
The facility requir.es exemptions from certain requirements of 10 CFR Part 50 and 10 CFR Part 70. These include:
(a) an exemption from the requirements of 10 CFR 70.24 for the criticality alarm monitors around the fuel-storage area; (b) an exemption from the requirement of 10 CFR Part 50, Appendix J - Option B, paragraph III.8, exempting the measured leakage rates from the main steam isolation valves from inclusion in the ombined leak rate for local leak rate tests (Section 6.2.6 of SSER 6);
(c) an exemption from the requirements of paragraph III.B of Option l
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anof 10 CFR Part 50, Appendix J, exempting leakage from the valve packing and the body-to-bonnet seal of valve IE51-F374 associated with containment penetration 1HC-44 from inclusion in the combined leakage rate for penetrations and valves subject to Type B and C tests (SERsuppo special circumstances regarding each exemption, except for Item (a) above, are identified in the referenced section of the safety evaluation l
report and the supplements thereto.
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Amendment No.-t05--
to U-6027%
LS 97 004 Page 3 of 3 Insert A
- and (d) a temporary partial exemption from the requirements of 10 CFR Part 50, Appendix A, General Design Criterion (GDC) 17 to allow plant operation with one offsite electrical power circuit that does not strictly conform to the capacity and capability requirements of GDC 17 due to voltage concerns addressed in IP Letter U-602796 dated July 22,1997, effective from the date ofissuance up to and including October 15,1997 (SER supporting Amendment 115 to Facility Operating License No. NPF-62) f l
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to U-602796 LS-97-004 Page1of4 Attached Marked-Up Pages of the Technical Specification Changes
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